Reinforced fuser roll construction

ABSTRACT

A fusing system for an electrostatic reproduction apparatus in which copy sheets are passed through pressure rollers applying heat and pressure to fuse a powder image on the copy sheets. One of the rotatable members which is heated to an elevated temperature to apply heat and pressure includes a core member which is covered with a reinforced layer of elastomeric material. The reinforced layer is formed by placing a jacket over a partially cured elastomeric layer and then spraying elastomeric material over the jacket until the desired thickness is formed. The jacket is made of one or more strands of a suitable material which may be crossed, woven, laid, braided or knitted.

United States Patent [191 Thettu et al.

[ 1 REINFORCED FUSER ROLL CONSTRUCTION [75] Inventors: Raghulinga R. Thettu, Webster; Edward G. Williams, Macedon, both of NY.

[73] Assignee: Xerox Corporation, Stamford,

Conn.

[22] Filed: May 21, 1973 [21] App]. No.: 361,923

[52] U.S. Cl 432/60, 161/89, 432/228, 29/132 [51] Int. Cl G03g 13/20 [58] Field of Search 432/59-62, 432/227-230; 226/190; 219/388, 469, 216; 100/93 RP; 355/3; 117/94, 16 ZA; 29/239, 132; 161/89, 206

[56] References Cited UNITED STATES PATENTS 2,679,572 5/1954 Workman 219/19 2,693,352 ll/1954 Bloom 432/234 2,695,248 11/1954 Ornitz et a1 432/234 2,867,112 l/1959 Krone 432/233 2,879,803 3/1959 Francois 117/94 3,256,002 6/1966 Hudson 432/62 3,291,466 12/1966 Aser et al. 432/62 I32 {fi z} 20o 1 Nov. 19, 1974 3,297,461 1/1967 Siddall 161/89 3,414,711 12/1968 Guyet et a1. 219/469 3,437,032 4/1969 Manghirmalani et al.. 100/93 3,466,210 9/1969 Wareham 117/94 3,562,084 2/1971 Shannon 161/89 3,637,416 l/l972 Misch et al. 29/132 3,686,731 8/1972 Koori et a1 29/132 3,730,794 5/1973 Ross 1. 29/132 3,775,208 11/1973 Grigoleit et a1 161/89 Primary Examiner-John J. Camby Assistant Examiner-Henry C. Yuen [57] ABSTRACT A fusing system for an electrostatic reproduction apparatus in which copy sheets are passed through pressure rollers applying heat and pressure to fuse a powder image on the copy sheets. One of the rotatable members which is heated to an elevated temperature to apply heat and pressure includes a core member which is covered with a reinforced layer of elastomeric material. The reinforced layer is formed by placing a jacket over a partially cured elastomeric layer and then spraying elastomeric material over the jacket until the desired thickness is formed. The jacket is made of one or more strands of a suitable material which may be crossed, woven, laid, braided or knitted.

7 Claims, 3 Drawing Figures for fusing a powder image to a substrate is to bring the powder into direct contact with a hot surface, such as a heated roller. The roller surface may be dry, i.e., no application of a liquid release agent to the surface of that roller as described for example, in U.S. Pat. Nos. 3,498,596, 3,539,161, and 3,666,247. Alternatively, the fuser roll surface may be wetted with a release agent, such as silicone oil as described in U. S. Pat. Nos. 3,268,351, and 3,256,002. A problem resulting from increased pressure and sharpness of the stripper fingers may result in damage to the surface of the fuser roll. Moreover, increased temperatures and pressure have caused deterioration to the fuser roll more rapidly resulting in greater costs and machine downtime. The present invention is an improved construction for the fuser roll surface to reduce significantly the damage on the fuser roll surface.

It is therefore the principal object of the present invention to improve heated pressure fusing roll devices. It is a further object of the present invention to reduce significantly the wear on the fuser roll.

It is a further object of the present invention to provide an improved construction of a heated roll fusing device.

These and other objects of the invention and further features thereof will be better understood upon reference to the following detailed description of the invention to be read in connection with the accompanying drawings wherein:

FIG. 1 illustrates schematically a xerographic reproducing apparatus incorporating a heated pressure fuser roll apparatus constructed in accordance with the present invention;

FIG. 2 is an isometric view of the fuser roll construction; and

FIG. 3 is an enlarged cross sectional view of the fuser apparatus under conditions with the copy sheet exiting the nip and illustrating details of the invention.

Referring now to the drawings, there is shown in FIG. 1 an embodiment of the subject invention in a suitable environment such as an automatic xerographic repro ducing machine. The automatic zerographic reproducing machine includes a xerographic plate or surface formed in the shape of a drum. The plate has a photoconductive layer or light receiving surface on a conductive backing, journaled in a frame to rotate in the direction indicated by the arrow. The rotation will cause the plate surface to sequentially pass a series of xerographic processing stations. For the purpose of the present disclosure the several xerographic processing stations in the path of movement of the plate surface may be described functionally as follows:

A charging station A, at which a uniform electrostatic charge is deposited on the photoconductive late; p An exposure station B, at which light or a radiation pattern of copy to be reproduced is projected onto the plate surface to dissipate the charge in the exposed areas thereof to thereby form a latent electrostatic image of the copy to be reproduced.

A developing station C, at which xerographic developing material, including toner particles having an electrostatic charge opposite that of the latent electrostatic image, is cascaded over the latent electrostatic image to form a toner powder imiage configuration of the copy being reproduced:

A transfer station D at which the toner powder image is electrostatically transferred from the plate surface to a transfer'material or a support surface; and

A drum cleaning and discharge staion E at which the plate surface is brushed to remove residual toner particles remaining thereon after image transfer and at which the plate is exposed to a relatively bright light source to effect substantially complete discharge of any residual electrostatic charge remaining thereon.

Further details of the aformementioned xerographic stations reference is made to U.S. Pat. No. 3,578,859 filed July 3, 1969 commonly assigned herewith.

In accordance with the invention at the fusing station F is a fusing assembly 101 comprising a fuser roll 103 and pressure roll 105 through which the copy sheet to be fused is advanced through the nip formed by contact of the fuser roll and pressure. The copy sheet is stripped from the fuser roll 103 by stripper fingers 112. The fuser roll comprises a rotating member having an elastic compressible coating 132 made of silicone rubber or any suitable heat resistant compressible material as described, for example, in the aforementioned patents. The rotating member may be internally heated by a heat source 134 as described for example, in U.S. Pat. No. 3,666,247 or externally heated as described in U.S. Pat. Nos. 3,498,596, and 3,539,161. The pressure roll comprises a rotating member which is covered with an elastic layer 142 preferably of a slightly higher durometer than the fuser roll coating 132 as described in the aforementioned patents.

Referring specifically to FIGS. 21 and 3 the fuser roll is arranged with circular undulations to enhance the release of the copy sheet from the fuser roll. The stripper fingers 112 are located in close proximity to the undulations to take advantage of the positive release .characeristics of the undulations. Undulations 150 may be formed by machining the core member 130 of the fuser roll to the prescribed outer diameter with an undulated or grooved profile. The core member is then prepared for elastic coating I32 and the required thickness of elastomer is sprayed onto the surface. The coating uniformly follows the surface of the core member to form the undulated profile. Alternatively, the undulations may be formed by spraying the coating onto a uniform cylindrical surface core member and masking areas during spraying to be undulated. The undulation may range from one or more in number. Each undulation may range in depth or height up to 10 times the thickness of the copy sheet and in width up to half the copy sheet width.

In accordance with the present invention the coating or layer 132 of the fuser roll is reinforced so that it will not tear or be easily scratched. This is accomplished by installing a reinforcing jacket 200 in the coating 132. Desirably the coating is sprayed and half cured before installing the jacket 200. The spraying of the coating is continued with the jacket in place until the desired thickness is reached. The jacket is made up of about 90 percent of the thickness of the total coating on the fuser roll. Preferably, the diameter of the strands is about 30 percent of the coating thickness. In other words for a coating thickness of mils the diameter of the strands is about 3 mils. The strands may be made of any suitable heat stable material with conformable characteristics different than the coating and having tensile strength exceeding that of the coating and elongation properties less than that of the coating. A preferred material is high temperature nylon Nomex, a registered trademark of Dupont Corp. of Wilm, Del. Other suitable materials are ceramic, plastic, metallic, elastomeric, or combinations thereof. The jacket desirably is in the form of strands arranged in a predetermined pattern. Typically, the strands may be crossed one over the other or non-run interlocking loops, or woven or knitted utilizing techniques known by those in the weaving industry.

It will be appreciated that the reinforcing jacket gives the elastomeric coating added mechanical strength. At the same time the jacket will not stretch to the extent that a' non-jacketed coating would. By this structure there is provided a stronger fuser roll construction lasting longer than the construction in the aforementioned patents without sacrificing the release and high quality fusing characteristicsdescribed. Also by this structure the sheet S bearing images I experience microconformability with the micro-undulations in an upon exiting the nip as best shown in FIG. 3.

While there have been shown and described and pointed out the fundamental novel features of the invention as applied to a preferred embodiment, it will be understood that various omissions, and substitutions and changes inthe form and details of the device illustrated and in its operation may be made by those skilled in the art without departing from the spirit of the invention.

What is claimed is:

1. In an electrostatic reproduction machine in which the fusing device for fusing powder images to copy sheets is accomplished by passing the powder image on the sheets through the nip of compressible rotatable members which apply heat and pressure, an improved fuser roll comprising:

a rigid core member;

a thin coating of elastomeric material covering the surface of said core member;

said elastomeric coating having a reinforcing jacket positioned thereon; said jacket being formed by a plurality of strands of heat stable material in a predetermined pattern;

wherein said reinforcing jacket material has a tensile strength exceeding that of said elastomeric coating; and

wherein said reinforcing jacket material has elongation characteristics less than that of said elastomeric coating.

2. A roll device acording to claim 1 wherein said strands have a diameter ranging from about 10 to percent of the thickness of the elastomeric coating.

3. A roll device according to claim 2 wherein said strands are made from high temperature nylon.

4. A roll device according to claim 2 wherein said strands are made from a material group consisting of ceramic, plastic, metallic, or combinations thereof.

5. A roll device according to claim 1 wherein said jacket is woven.

6. A roll device according to claim 1 wherein said jacket is knitted.

7. A roll device according to claim 1 wherein said reinforcing jacket material has deformable characteristics different than said elastomeric coating. 

1. In an electrostatic reproduction machine in which the fusing device for fusing powder images to copy sheets is accomplished by passing the powder image on the sheets through the nip of compressible rotatable members which apply heat and pressure, an improved fuser roll comprising: a rigid core member; a thin coating of elastomeric material covering the surface of said core member; said elastomeric coating having a reinforcing jacket positioned thereon; said jacket being formed by a plurality of strands of heat stable material in a predetermined pattern; wherein said reinforcing jacket material has a tensile strength exceeding that of said elastomeric coating; and wherein said reinforcing jacket material has elongation characteristics less than that of said elastomeric coating.
 2. A roll device acording to claim 1 wherein said strands have a diameter ranging from about 10 to 90 percent of the thickness of the elastomeric coating.
 3. A roll device according to claim 2 wherein said strands are made from high temperature nylon.
 4. A roll device according to claim 2 wherein said strands are made from a material group consisting of ceramic, plastic, metallic, or combinations thereof.
 5. A roll device according to claim 1 wherein said jacket is woven.
 6. A roll device according to claim 1 wherein said jacket is knitted.
 7. A roll device according to claim 1 wherein said reinforcing jacket material has deformable characteristics different than said elastomeric coating. 